1. Field of the Invention
The present invention relates to an engine enclosure for a construction vehicle and, more particularly, to an engine enclosure for a construction vehicle having a screening construction, in which ambient air, as taken into an engine room from ambient air passing holes formed in an engine hood and engine side covers enclosing the engine, for cooling a heat exchanger is guided to flow to a fan without contacting with a muffler positioned in the engine room.
2. Related Art
If the construction vehicle such as a bulldozer is of the ambient air intake type in which a wind for cooling a radiator arranged on the vehicle front side is established by a fan, the cooling wind having passed the radiator entrains the hot air in the engine room to the operator. It is, therefore, customary to adopt radiator cooling means of the ambient air forcing type, in which the ambient air is taken into the engine room and forced to pass the radiator to the vehicle front side.
With this means being adopted, the ambient air is raised in temperature by the high heat in the engine room, especially by the radiation heat from the engine exhaust muffler. Thus, there arises a problem that the radiator cooling efficiency is low.
A technique for improving the low cooling effect has been disclosed in Japanese Patent Laid-Open No. 74036/1975(U.S. Pat. No. 3,866,580). In order to prevent the temperature of the cooling wind taken into the engine enclosure by the fan from being raised by the radiation heats from the engine and the muffler and to prevent the radiation heat from transferring to the heat exchanger such as the radiator, according to the Publication, the inside of the engine enclosure is partitioned into a chamber including the muffler and the engine and a chamber including the fan and the heat exchanger. The technique of the Publication is further constructed by forming an ambient air inlet port in the enclosure of the chamber on the side of the fan and the heater exchanger, and by disposing radiation heat releasing means on the side of the muffler and the engine room.
According to the aforementioned prior art, it is possible to attain the effects to improve the cooling efficiency and to lower the noise. In order to partition the engine enclosure to dispose the heat exchanger and the fan therein, however, it is necessary to add a separate construction of an air intake passage for introducing the ambient air into the isolated heat exchanger and fan chambers. As a result, the construction to screen or isolate the inside of the engine enclosure into the chamber for the engine and the muffler and the chamber for the heat exchanger and the fan is troubled by a problem that the engine enclosure itself is longitudinally elongated to complicate and enlarge the structure thereby to raise the manufacture cost and the final price.
An object of the invention is to provide an engine enclosure for a construction vehicle which can be simply constructed and small-sized while improving the cooling efficiency and lowering the noise.
According to the invention of a first aspect, there is provided an engine enclosure for a construction vehicle of the cooling type, in which the cooling ambient air taken into an engine room from ambient air inlet ports formed in an engine hood enclosing the engine and in two engine side covers is forced by a fan toward a heat exchanger in front of the engine, comprising: an ambient air screening wall surrounding a muffler, which is disposed in an over-engine space defined in the engine room by the engine hood and the two engine side covers, so that the taken cooling ambient air may flow to the fan without any contact with the muffler.
With the ambient air screening wall, according to the invention, the cooling ambient air flows to the fan without contacting with the muffler. Therefore, the air around the muffler especially at a high temperature in the engine room and the cooling ambient air to be taken from the engine hood and the engine side covers can be screened from each other to reduce the temperature rise of the cooling ambient air to be fed to the heat exchanger such as the radiator or the oil cooler. As a result, it is possible to improve the cooling efficiency.
By the ambient air screening wall, on the other hand, the cooling ambient air taken flows to the fan without contacting with the muffler so that the chamber including the muffler and the engine and the chamber including the fan and the heat exchanger need not be isolated to make a simple construction and to reduce the size. As a result in the improvement in the cooling efficiency, moreover, the fan RPM (Revolutions Per Minute) can be reduced at the same heat radiation thereby to lower the noise.
In the invention, the ambient air screening wall may have any construction if the cooling ambient air taken flows to the fan without contacting the muffler.
According to the invention of a second aspect, the ambient air screening wall around the muffler includes: a first muffler screening partition disposed in the engine hood so that the ambient air taken from the ambient air inlet port formed in the engine hood may flow without contacting with the upper face or front face sides of the muffler; and second muffler screening partitions disposed in the two engine side covers so that the ambient air taken from the ambient air inlet ports formed in the two engine side covers may flow without contacting with the two sides of the muffler.
In addition to the effects of the first aspect, according to this invention, the ambient air screening wall is constructed to include the first muffler screening partition disposed in the engine hood and second muffler screening partitions disposed in the two engine side covers, so that the ambient air flow, as might otherwise contact with the muffler, can be screened at a low cost by the simple construction.
On the other hand, the cooling ambient air does not flow around the muffler. Therefore, the ambient air is not exposed to the radiation from the muffler so that the cooling efficiency of the heat exchanger can be enhanced.
According to the invention of a third aspect, the first muffler screening partition disposed in the engine hood is constructed of an ambient air passing duct to the fan, as attached to the inner side of the engine hood in a manner to confront the ambient air inlet port of the engine hood.
In this invention, the cooling ambient air taken from above the engine room is entrained to the fan without contacting with the muffler positioned on the outer side of the duct so that a contribution is made to the improvement in the cooling efficiency of the heat exchanger.
In the invention, the partition confronting the muffler side of the duct is preferably inclined downward toward the fan or formed into a gentle curve.
According to the invention of a fourth aspect, the second muffler screening partitions disposed in the two engine side covers are constructed of ambient air screening plates to the muffler, as attached at a spacing from the side covers to the inner sides of the side covers in a manner to confront the ambient air inlet ports of the two engine side covers.
In this invention, the cooling ambient air taken from the sides of the engine room flows along the ambient air screening plates so that its flow is smoothened. Moreover, the ambient air is guided to the fan without any contact thereby to lower the ambient noise.
In the invention, it is preferred that the ambient air screening plates are inclined transversely obliquely from the side covers to the fan.
According to the invention of a fifth aspect, the ambient air passing duct to the fan, as attached to the engine hood, has an ambient air guide portion inclined from the engine hood toward the fan while covering the upper side and the front side of the muffler.
In this invention, the flow of the cooling ambient air taken from above the engine room is smoothened to the fan so that the cooling efficiency can be improved.
According to the invention of a sixth aspect, the ambient air screening plates to the muffler, as attached to the inner sides of the two side covers, have guide portions for guiding the ambient air flow toward the fan.
In this invention, the flows of the cooling ambient air taken from the sides of the engine room are smoothened to the fan so that the cooling efficiency can be improved.